FEILD OF THE INVENTION
The field of the disclosure relates generally to pumping systems in a gas
turbine engines and, more particularly, to a method and system for pumping
oil in a gas turbine engine using a centrifugal pump.
BACKGROUND OF THE INVENTION
Scavenge oil, i.e., oil drained to an oil sump after lubricating bearings in gas
turbine engines, is typically sent to a scavenge oil tank after lubricating the
bearings. At least some known methods of transporting scavenge oil to a
scavenge oil tank include a gravitational drain through a hot frame. As gas
turbine engines become more powerful, the temperatures the hot frame is
exposed to also increase. Transporting scavenge oil in the hot frame can cause
the scavenge oil to coke because of the high temperatures the hot frame is
exposed to. To reduce scavenge oil coking, cooling air is supplied to the hot
frame to cool the scavenge oil as it is transported through the hot frame.
Additionally, the hot frame strut thickness is increased to protect the scavenge
oil drain piping. An additional cooling air system and a thicker hot frame strut
adds weight to the gas turbine engine.
BRIEF DESCRIPTION OF THE INVENTION
In one aspect, a pump is provided. The pump includes a first rotatable
member including a radially inward facing groove having an edge. The first
rotatable member configured to receive a plurality of flows of fluid over the
edge. The first rotatable member configured to rotate at a first angular
velocity. The pump also includes a second rotatable member including a
collector configured to rotate at a second angular velocity. The second
rotatable member also includes a plurality of scoop tubes extending radially
outwardly from the collector. Each scoop tube of the plurality of scoop tubes
includes a first end coupled in flow communication to the collector and a
second end including an inlet opening extending into the groove. The second
3
end is curved such that the inlet opening is open in a direction of rotation of
the second rotatable member. The inlet opening is configured to scoop a fluid
collected in the groove.
In another aspect, a method of pumping a fluid using a pump that includes a
first rotatable member including a circumferential groove on a radially inner
surface and a second rotatable member including one or more scoop tubes
extending into the groove. The method includes receiving a flow of fluid at
the first rotatable member. The first rotatable member circumscribes the
second rotatable member. The method also includes centrifugally collecting
the flow of fluid in a radially outer portion of the groove. The method further
includes scooping a portion of the centrifugally collected fluid into the one or
more scoop tubes. The method also includes channeling the scooped fluid to a
fluid scavenge system.
In yet another aspect, a gas turbine engine is provided. The gas turbine engine
includes a high pressure power shaft rotationally coupled to a high pressure
compressor and a high pressure turbine. The gas turbine engine also includes
a low pressure power shaft rotationally coupled to a low pressure compressor
and a low pressure turbine. The gas turbine engine further includes a pump
including a first rotatable member including a radially inward facing groove
having an edge. The first rotatable member configured to receive a plurality
of flows of fluid over the edge. The low pressure power shaft configured to
rotate the first rotatable member at a first angular velocity. The pump also
includes a second rotatable member including a collector rotationally coupled
to the high pressure power shaft and configured to rotate at a second angular
velocity. The second rotatable member also includes a plurality of scoop
tubes extending radially outwardly from the collector. Each scoop tube of the
plurality of scoop tubes includes a first end coupled in flow communication to
the collector and a second end including an inlet opening extending into the
groove. The second end curved such that the inlet opening is open in a
4
direction of rotation of the second rotatable member. The inlet opening is
configured to scoop a fluid collected in the groove.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present disclosure
will become better understood when the following detailed description is read
with reference to the accompanying drawings in which like characters
represent like parts throughout the drawings, wherein:
FIGS. 1-4 show example embodiments of the method and apparatus described
herein.
FIG. 1 is a schematic view of a gas turbine engine.
FIG. 2 is a schematic view of a low pressure turbine within a gas turbine
engine.
FIG. 3 is a schematic diagram of a scavenge oil pump.
FIG. 4 is a schematic diagram of rotating oil groove or plenum.
Although specific features of various embodiments may be shown in some
drawings and not in others, this is for convenience only. Any feature of any
drawing may be referenced and/or claimed in combination with any feature of
any other drawing.
Unless otherwise indicated, the drawings provided herein are meant to
illustrate features of embodiments of the disclosure. These features are
believed to be applicable in a wide variety of systems comprising one or more
embodiments of the disclosure. As such, the drawings are not meant to
include all conventional features known by those of ordinary skill in the art to
be required for the practice of the embodiments disclosed herein.
5
DETAILED DESCRIPTION
In the following specification and the claims, reference will be made to a
number of terms, which shall be defined to have the following meanings.
The singular forms “a”, “an”, and “the” include plural references unless the
context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or
circumstance may or may not occur, and that the description includes
instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and
claims, may be applied to modify any quantitative representation that could
permissibly vary without resulting in a change in the basic function to which it
is related. Accordingly, a value modified by a term or terms, such as “about”,
“approximately”, and “substantially”, are not to be limited to the precise value
specified. In at least some instances, the approximating language may
correspond to the precision of an instrument for measuring the value. Here
and throughout the specification and claims, range limitations may be
combined and/or interchanged; such ranges are identified and include all the
sub-ranges contained therein unless context or language indicates otherwise.
The following detailed description illustrates embodiments of the disclosure
by way of example and not by way of limitation. It is contemplated that the
disclosure has general application to a method and system for circulating oil in
an aircraft engine.
Embodiments of the pump described herein pump scavenge oil to an turbine
rear frame (TRF). The pump includes a rotating oil plenum circumscribing a
rotating tube assembly. Scavenge oil drains into the rotating oil plenum which
rotates to form a uniform pool of oil. Rotating tube assembly includes a
plurality of scoop tubes extending into the uniform pool of oil. Rotation of
6
rotating tube assembly channels scavenge oil into the scoop tubes. The scoop
tubes channel scavenge oil axially aft to an TRF. Scavenge oil drains through
the TRF to a scavenge oil system. In an exemplary embodiment, the rotating
oil plenum and the rotating tube assembly rotate in opposite directions. In an
alternative embodiment, the rotating oil plenum and the rotating tube
assembly rotate in the same direction. In an alternative embodiment, the
rotating oil plenum is configured to rotate and the rotating tube assembly is
configured to remain stationary.
The pumps and scavenge oil transport systems described herein offer
advantages over known methods of transporting scavenge oil in a gas turbine
engine. More specifically, some known methods and systems of transporting
scavenge oil include transporting scavenge oil through a turbine center frame
(TCF). TCFs typically operate at higher temperatures, requiring cooling air
and TCF struts to prevent scavenge oil coking in the scavenge oil drain line.
Draining scavenge oil through a cooler TRF removes the need for cooling air
in the TCF and allows the TCF to use thinner struts. A thinner TCF strut
reduces the weight of the engine and improves the performance of the engine.
FIG. 1 is a schematic cross-sectional view of a gas turbine engine 110 in
accordance with an exemplary embodiment of the present disclosure. FIG. 2
is a schematic cross-sectional view of a (LP) low pressure turbine 130 within
gas turbine engine 110 in accordance with an exemplary embodiment of the
present disclosure. In the example embodiment, gas turbine engine 110 is a
high-bypass turbofan jet engine 110, referred to herein as “turbofan engine
110.” As shown in FIG. 1, turbofan engine 110 defines an axial direction A
(extending parallel to a longitudinal centerline 112 provided for reference) and
a radial direction R. In general, turbofan 110 includes a fan section 114 and a
core turbine engine 116 disposed downstream from fan section 114.
Exemplary core turbine engine 116 depicted generally in FIG. 1 includes a
substantially tubular outer casing 118 that defines an annular inlet 120. Outer
7
casing 118 and a substantially tubular inner casing 119 encases, in serial flow
relationship, a compressor section including a booster or low pressure (LP)
compressor 122 and a high pressure (HP) compressor 124; a turbine center
frame (TCF) 139 and an turbine rear frame (TRF) 141; a combustion section
126; a turbine section including a high pressure (HP) turbine 128 and LP
turbine 130; and a jet exhaust nozzle section 132. The volume between outer
casing 118 and inner casing 119 forms a plurality of cavities 121. A high
pressure (HP) shaft or spool 134 drivingly connects HP turbine 128 to HP
compressor 124. A low pressure (LP) shaft or spool 136 drivingly connects
LP turbine 130 to LP compressor 122. The compressor section, combustion
section 126, turbine section, and nozzle section 132 together define a core air
flowpath 137.
Referring to FIG. 2, a scavenge oil pump 143 is coupled to HP shaft or spool
134 and LP shaft or spool 136. A scavenge oil system 145 is disposed within
cavity 121. Scavenge oil pump 143 and scavenge oil system 145 are coupled
in flow communication by a scavenge oil drain pipe 147. Scavenge oil drain
pipe 147 extends generally along axial direction A aft of scavenge oil pump
143 to TRF 141. Scavenge oil drain pipe 147 extends generally along radial
direction R through TRF 141 to scavenge oil system 145.
Referring back to FIG. 1, for the embodiment depicted, fan section 114
includes a variable pitch fan 138 having a plurality of fan blades 140 coupled
to a disk 142 in a spaced apart manner. As depicted, fan blades 140 extend
outwardly from disk 142 generally along radial direction R. Each fan blade
140 is rotatable relative to disk 142 about a pitch axis P by virtue of fan blades
140 being operatively coupled to a suitable pitch change mechanism 144
configured to collectively vary the pitch of fan blades 140 in unison. Fan
blades 140, disk 142, and pitch change mechanism 144 are together rotatable
about longitudinal axis 112 by LP shaft 136 across a power gear box 146.
Power gear box 146 includes a plurality of gears for adjusting the rotational
8
speed of fan 138 relative to LP shaft 136 to a more efficient rotational fan
speed.
Referring still to the exemplary embodiment of FIG. 1, disk 142 is covered by
rotatable front hub 148 aerodynamically contoured to promote an airflow
through plurality of fan blades 140. Additionally, exemplary fan section 114
includes an annular fan casing or outer nacelle 150 that circumferentially
surrounds fan 138 and/or at least a portion of core turbine engine 116. It
should be appreciated that nacelle 150 may be configured to be supported
relative to core turbine engine 116 by a plurality of circumferentially-spaced
outlet guide vanes 152. In the exemplary embodiment, outlet guide vanes 152
include engine oil heat exchangers. Moreover, a downstream section 154 of
nacelle 150 may extend over an outer portion of core turbine engine 116 so as
to define a bypass airflow passage 156 therebetween.
During operation of turbofan engine 110, a volume of air 158 enters turbofan
110 through an associated inlet 160 of nacelle 150 and/or fan section 114. As
volume of air 158 passes across fan blades 140, a first portion of air 158 as
indicated by arrows 162 is directed or routed into bypass airflow passage 156
and a second portion of air 158 as indicated by arrow 164 is directed or routed
into core air flowpath 137, or more specifically into LP compressor 122. The
ratio between first portion of air 162 and second portion of air 164 is
commonly known as a bypass ratio. The pressure of second portion of air 164
is then increased as it is routed through HP compressor 124 and into
combustion section 126, where it is mixed with fuel and burned to provide
combustion gases 166.
Combustion gases 166 are routed through HP turbine 128 where a portion of
thermal and/or kinetic energy from combustion gases 166 is extracted via
sequential stages of HP turbine stator vanes 168 and HP turbine rotor blades
170. HP turbine stator vanes 168 are coupled to outer casing 118. HP turbine
rotor blades 170 are coupled to HP shaft or spool 134. Rotation of HP turbine
9
rotor blades 170 causes HP shaft or spool 134 to rotate, thereby supporting
operation of HP compressor 124. Combustion gases 166 are then routed
through LP turbine 130 where a second portion of thermal and kinetic energy
is extracted from combustion gases 166 via sequential stages of LP turbine
stator vanes 172 and LP turbine rotor blades 174. LP turbine stator vanes 172
are coupled to outer casing 118. LP turbine rotor blades 174 are coupled to
LP shaft or spool 136. Rotation of LP turbine rotor blades 174 causes LP
shaft or spool 136 to rotate, thereby supporting operation of LP compressor
122 and/or rotation of fan 138.
Referring to FIG. 2, Oil lubricates components of gas turbine engine 110.
Scavenge oil collects in sumps and drains to scavenge oil pump 143.
Scavenge oil pump 143 channels a plurality of flows of scavenge oil to
scavenge oil drain pipe 147 which channels scavenge oil to scavenge oil
system 145.
Referring back to FIG. 1, Combustion gases 166 are subsequently routed
through jet exhaust nozzle section 132 of core turbine engine 116 to provide
propulsive thrust. Simultaneously, the pressure of first portion of air 162 is
substantially increased as first portion of air 162 is routed through bypass
airflow passage 156 before it is exhausted from a fan nozzle exhaust section
176 of turbofan 110, also providing propulsive thrust. HP turbine 128, LP
turbine 130, and jet exhaust nozzle section 132 at least partially define a hot
gas path 178 for routing combustion gases 166 through core turbine engine
116.
It should be appreciated, however, that exemplary turbofan engine 110
depicted in FIG. 1 and FIG. 2 is by way of example only, and that in other
exemplary embodiments, turbofan engine 110 may have any other suitable
configuration. It should also be appreciated, that in still other exemplary
embodiments, aspects of the present disclosure may be incorporated into any
other suitable gas turbine engine. For example, in other exemplary
10
embodiments, aspects of the present disclosure may be incorporated into, e.g.,
a turboprop engine.
FIG. 3 is a schematic diagram of scavenge oil pump 143. Scavenge oil pump
143 includes a rotating oil groove or plenum 302 circumscribing a rotating
scoop tube assembly 304. FIG. 4 is a schematic diagram of rotating oil groove
or plenum 302. Rotating oil plenum 302 includes a cylinder 306 and two side
walls 308 coupled to and extending generally along radial direction R inward
from each end of cylinder 306 forming a U-shaped plenum 310 to contain a
uniform pool of oil 312. Rotating oil plenum 302 is rotationally coupled to LP
shaft or spool 136. Rotating scoop tube assembly 304 includes a plurality of
scoop tubes 314 extending generally along radial direction R outward from
centerline 112 into uniform pool of oil 312. Scoop tubes 314 are coupled in
flow communication with stationary scavenge oil drain pipe 147 at the bottom
of the sump. Rotating scoop tube assembly 304 is rotationally coupled to HP
shaft or spool 134.
During operation of scavenge oil pump 143, scavenge oil collects in sumps
and drains into rotating oil plenum 302. LP shaft or spool 136 rotates rotating
oil plenum 302 with a first angular velocity as indicated by arrow 316.
Centrifugal force from rotation of rotating oil plenum 302 forms drained
scavenges oil into uniform pool of oil 312. HP shaft or spool 134 rotates
rotating scoop tube assembly 304 with a second angular velocity as indicated
by arrow 318. First angular velocity 316 rotates in an opposite direction from
second angular velocity 318 because HP shaft or spool 134 rotates counter to
LP shaft or spool 136. Scavenge oil is channeled into scoop tubes 314 which
channels scavenge oil into stationary scavenge oil drain pipe147 as indicated
by arrows 320. Scavenge oil drain pipe 147 channels oil to scavenge oil
system 145 located at the bottom of gas turbine engine 110 (shown in FIG. 1).
In an alternative embodiment, rotating oil plenum 302 and rotating scoop tube
assembly 304 are configured to rotate in the same direction rather than
11
opposite directions. Rotating oil plenum 302 rotates in the direction of a third
angular velocity as indicated by arrow 322. The rotational direction of second
angular velocity 318 and third angular velocity 322 are equal. However, the
magnitude of rotational speed of second angular velocity 318 and third
angular velocity 322 are unequal to channel scavenge oil into scoop tubes 314.
In an alternative embodiment, rotating oil plenum 302 is configured to rotate
and rotating scoop tube assembly 304 is configured to remain stationary.
Rotating oil plenum 302 rotates in the direction of first angular velocity 316.
Rotation of rotating oil plenum 302 channels scavenge oil into scoop tubes
314.
The above-described pump provides an efficient method for transporting
scavenge oil in a gas turbine engine. Specifically, the above-described pump
pumps scavenge oil to an inner radius of a gas turbine engine. Scavenge oil is
channeled aft to a TRF which experiences cooler operating temperatures than
TCFs. Channeling scavenge oil through a TRF allows reduction of the
thickness of the TFC. Reduced TFC strut thickness reduces the weight of the
gas turbine engine. As such, channeling scavenge oil through a TRF improves
the performance of the gas turbine engine. Additionally, channeling scavenge
oil through a TRF eliminates the need for cooling air in the TFC to reduce
scavenge oil coking.
Exemplary embodiments of a pump for scavenge oil are described above in
detail. The pump, and methods of operating such systems and devices are not
limited to the specific embodiments described herein, but rather, components
of systems and/or steps of the methods may be utilized independently and
separately from other components and/or steps described herein. For example,
the methods may also be used in combination with other systems requiring
scavenge oil pumping, and are not limited to practice with only the systems
and methods as described herein. Rather, the exemplary embodiment can be
12
implemented and utilized in connection with many other machinery
applications that are currently configured to receive and accept pumps.
Example methods and apparatus for a pump in a gas turbine engine are
described above in detail. The apparatus illustrated is not limited to the
specific embodiments described herein, but rather, components of each may
be utilized independently and separately from other components described
herein. Each system component can also be used in combination with other
system components.
This written description uses examples to describe the disclosure, including
the best mode, and also to enable any person skilled in the art to practice the
disclosure, including making and using any devices or systems and
performing any incorporated methods. The patentable scope of the disclosure
is defined by the claims, and may include other examples that occur to those
skilled in the art. Such other examples are intended to be within the scope of
the claims if they have structural elements that do not differ from the literal
language of the claims, or if they include equivalent structural elements with
insubstantial differences from the literal languages of the claims.
13
WE CLAIM:
1. A pump (300) comprising:
a first rotatable member (302) comprising a radially inward facing groove
(310) having an edge (308), said first rotatable member (302) configured to
receive a plurality of flows of fluid over the edge (308), said first rotatable
member (302) configured to rotate at a first angular velocity (316); and
a second rotatable member (304) comprising:
a collector (304) configured to rotate at a second angular velocity
(318); and
a plurality of scoop tubes (314) extending radially outwardly from
said collector (304), each scoop tube of said plurality of scoop tubes (314)
comprising:
a first end coupled in flow communication to said collector
(304); and
a second end comprising an inlet opening extending into
the groove (310), said second end curved such that said inlet
opening is open in a direction of rotation of said second rotatable
member (304), said inlet opening configured to scoop a fluid
collected in said groove (310).
2. The pump (300) as claimed in Claim 1, wherein said first angular
velocity (316) is opposite with respect to said second angular velocity (318).
3. The pump (300) as claimed in Claim 1, wherein said first rotatable
member (302) configured to rotate in the same direction as the direction of
rotation of said second rotatable member (304).
14
4. The pump (300) as claimed in Claim 3, wherein said first angular
velocity (316) is less then said second angular velocity (318).
5. The pump (300) as claimed in Claim 1, wherein said first rotatable
member (302) configured to receive a plurality of flows of fluid over the edge
(308) from a plurality of sumps.
6. The pump (300) as claimed in Claim 1, wherein said fluid
comprises oil.
7. A gas turbine engine (110) comprising:
a high pressure power shaft (134) rotationally coupled to a high pressure
compressor (124) and a high pressure turbine (128);
a low pressure power shaft (136) rotationally coupled to a low pressure
compressor (122) and a low pressure turbine (130);
a pump (300) comprising:
a first rotatable member (302) comprising a radially inward facing groove
(310) having an edge (308), said first rotatable member (302) configured to
receive a plurality of flows of fluid over the edge (308), said low pressure power
shaft configured to rotate said first rotatable member (302) at a first angular
velocity (316); and
a second rotatable member (304) comprising:
a collector (304) rotationally coupled to said high pressure power
shaft and configured to rotate at a second angular velocity (318); and
a plurality of scoop tubes (314) extending radially outwardly from
said collector (304), each scoop tube of said plurality of scoop tubes (314)
comprising:
15
a first end coupled in flow communication to said collector
(304); and
a second end comprising an inlet opening extending into the groove (310),
said second end curved such that said inlet opening is open in a direction of
rotation of said second rotatable member (304), said inlet opening configured to
scoop a fluid collected in said groove (310).
8. The gas turbine engine (110) as claimed in Claim 7, wherein said
first rotatable member (302) configured to rotate in a direction opposite a
direction of rotation of said second rotatable member (304).
9. The gas turbine engine (110) as claimed in Claim 7, wherein said
first rotatable member (302) configured to rotate in the same direction as the
direction of rotation of said second rotatable member (304).
10. The gas turbine engine (110) as claimed in Claim 7, wherein said
first rotatable member (302) is configured to rotate and said second rotatable
member (304) is configured to remain stationary.